Effects of wastewater disinfection on triclosan and detection of a hydroxylated polybrominated diphenyl ether in wastewater effluent

Abstract

Triclosan, an antimicrobial agent used in many personal care products, is chlorinated in wastewater treatment plants (WWTPs) giving rise to chlorinated triclosan derivatives (CTDs). Through photolysis in natural waters, these compounds yield specific polyhalogenated dibenzo-p-dioxins. Hydroxylated polybrominated diphenyl ethers (OH-PBDEs), which have natural and anthropogenic sources and are of similar structure to triclosan, may react similarly. It is important to understand the loads of these chemicals emanating from WWTPs and how disinfection practices influence these concentrations. Using pre-concentration of water samples by solid phase extraction followed quantification using liquid chromatography tandem mass spectrometry, the yield of CTDs has been quantified at WWTPs using different disinfection treatments. Triclosan was detected in all wastewater samples from < 14 – 1609 pM (< 36 – 465 ng/L). The sum of CTDs in chlorinated effluents were higher than other effluents, ranging from 63 – 80 pM (21.5 – 27.2 ng/L). Wastewater from a WWTP that used reduced chlorination had 17.4 – 23.4 pM (3.9 – 4.7 ng/L) of total CTDs. In wastewater that was not disinfected or UV irradiated, concentrations of CTDs were 1.9 – 29.4 pM (0.7 – 10.1 ng/L). Laboratory ozonation of wastewater reduced total CTDs significantly from 10 pM (3.4 ng/L) to 1.5 pM (0.5 ng/L). The estimates of triclosan-derived dioxin loadings to US surface water ranged from 0.3 – 207 g TEQ/year (0.01 – 8.3% of US air emissions of dioxins). These estimates are significant due to their unique discharge directly into the aquatic environment. The OH-PBDE, 6-OH-BDE-47, was detected in some extracts at the highest levels detected in wastewater yet – up to 33.6 pM (1.8 ng/L). This report is the first to confirm wastewater as a source of 6-OH-BDE-47 to a fresh water environment.